Transcranial direct current stimulation is a neurophysiological technique able to modulate the excitability of the biological tissue of the central and peripheral nervous system, through the delivery, for a finite time length, of an electrical field generating a current flow and a net relative electrical charge passing through the biological tissue itself (Priori et al, 2003). The difference between direct current stimulation and other electrical stimulations is the presence of this net positive charge passing through the tissue and obtained through mono-directional currents, called “direct currents”. Physical and biochemical mechanisms induced in the nervous tissue by the administration of direct currents are not yet completely clear (Ardolino et al, 2005). Several studies (Lang et al, 2004; Nitsche et al, 2006) hypothesize that the application of constant electrical fields for a certain amount of time induce electrochemical mechanisms producing the excitation or inhibition of the nervous tissue also through the activation of the second-messenger system, and generating effects lasting also for some weeks (Liebetanz et al, 2002; Nietsche et al, 2002). Direct current stimulation is applied through a current generator connected to a pair (or more) electrodes applied on the skin, soaked with a saline solution, so that the electrical charge can be transmitted to the tissue. There usually are two electrodes, the first one, known as the “active” electrode, is placed over the part of the tissue that should be treated, the second one is the “reference” electrode. Different applications have different electrode montages. The type of treatment refers to the polarity of the active electrode respect to the reference electrode: if the electric potential of the active electrode is higher than that of the reference electrode, the treatment is called “anodal”, otherwise it is “cathodal”. In some particular cases, more active electrodes are placed on the scalp to treat symmetric brain regions, and only one reference electrode is used to guarantee the correct current flow. Current density, defined as the ratio between the electrical current to the tissue and the area of the active electrode, is usually between 0.01 and 0.5 mA/cm2.is. For instance, a 30 cm2 electrode can deliver currents ranging from 1 to 5 mA. The duration of the treatment ranges from 10 to 30 minutes. The net charge to the human body is calculated as the time integral of the electrical current applied. The impedance on the current generator is mainly due to the resistance of the electrodes that are, therefore, kept wet though saline solutions and conductive gels. To ensure safety, the system do not apply potential differences above 30 V, thus limiting the current delivered in the case of excessive load increase. The treatments applied do not exceed one administration per day and for a limited number of days. At present, direct current stimulation has been recognized as an effective adjuvant treatment for several neurological and neuropsychiatric diseases, such as Alzheimer disease, Parkinson's disease, post-stroke aphasia, lateral amyotrophic sclerosis, ictus, dystonia, headache, Tourette syndrome (Antal et al, 2008; Boggio et al, 2006; Boggio et al, 2007; Ferrucci et al, 2008a; Monti et al, 2008; Mrakic-Sposta et al, 2008; Quartarone et al, 2007; Wu et al, 2008). In addition, direct current stimulation is under study for the treatment of other pathologies and for the modulation of particular behaviors in normal subjects (Antal and Paulus, 2008). Some applications of the technique have been proposed also for the control of muscular fatigue (Cogiamanian et al, 2007), showing an increase of 20% of endurance time, and also for the modulation of deception processes (Priori et al, 2008), of moral choices, and for enhancing learning and decision making processes (Fecteau et al, 2007; Ferrucci et al, 2008b; Fregni et al, 2008a; Fregni et al, 2008b). Safety and efficacy of the treatment depend on a correct administration, that should be properly tested and verified (Nietsche et al, 2003). Conversely, if the treatment is administered through a wrong montage, and, moreover, through wrong stimulation intensities, or frequency of application, adverse effects cannot be excluded. Hence, direct current stimulation could be potentially dangerous if the subject is left free to administer the treatment by himself, as well as in the case of the administration of particular active pharmacological principles. For this reason, at present, systems for direct current stimulations are given only to specialized personnel, who are authorized to administer the treatment to patients in specific clinical areas, verifying the frequency of administration, stimulation parameters, and electrode montages. This, however, limits the range of possible application of the direct current stimulation. Because the treatment can be delivered only in specialized clinical centers and because it has to be done for a number of consecutive days, the associated costs (personnel, subjects'hospitalization, transport or housing of subjects who must reach the specialized centers for some consecutive days, and costs deriving from the inability of the treated subject to make his own activities) are a limitation for the widespread diffusion of the treatment. Conversely, an application that is controlled by specialized personnel but delivered by the patient himself at home could increase the efficacy of this methodology thus enhancing its applicability and diffusion.